The present invention is related to a pipette.
Pipettes are devices for gauging and transferring liquids. They are often realised as repetition or multi pipettes, which permit the stepwise delivery of a liquid from a syringe. A repetition pipette is known from DE 29 26 691 C2, the entire contents of which are incorporated herein by reference, respectively, or U.S. Pat. No. 4,406,170 A1, the entire contents of which are incorporated herein by reference, respectively, which describes the repetition mechanism of the repetition pipette in particular. It also describes the fastening of a syringe of the system on the repetition pipette. For this purpose, the syringe has a syringe flange, which is insertable into a laterally open, essentially U-shaped groove from out one side. An axial pressing spring fixes the inserted syringe flange in the groove. For the connection of the syringe plunger with a plunger setting device, there is an insert element, which receives an end portion of the syringe plunger between two cheeks. The cheeks can be pressed against the syringe plunger by means of a flap-shaped clamping member, whose actuation lever projects out of the housing via an opening. This syringe fixture has the disadvantage that the syringe has to be touched by the hand for insertion and coupling with the plunger setting device, or for uncoupling and take-out, respectively.
DE 43 41 229 C2, the entire contents of which are incorporated herein by reference, respectively or U.S. Pat. No. 5,620,660 A1, the entire contents of which are incorporated herein by reference, respectively, respectively, proposes a syringe system better suited for manual operation, with a syringe which can be simply axially thrusted into the pipette or axially removed from the same, respectively. This pipette system has a syringe featuring a fastening portion and a syringe plunger and a pipette which has an accommodation for the fastening portion and an accommodation body with a plunger accommodation for the syringe plunger. Further, there are fastening devices for reversibly fastening the fastening portion and the syringe plunger in the accommodations, and plunger setting devices for shifting the accommodation body in the pipette housing. The fastening portion and the syringe plunger are axially thrustable into their fastening positions via axial openings of their accommodations. The fastening devices have radially closable gripping devices for fastening the fastening portion and the syringe plunger in the fastening positions. The gripping devices have syringe gripping levers pivotally mounted in the pipette housing, and plunger gripping levers pivotally mounted in the pipette body. The syringe gripping levers and the plunger gripping levers are realised with two arms, a gripping arm and an actuation arm, wherein the syringe gripping levers have contact sites on the inner sides of their actuation arms, which, by actuating their actuation arms at the outside, are turnable against the actuation arms of the plunger gripping levers and which actuate the plunger gripping levers. Through this it is obtained that the syringe and the pipette are connectable with each other by a purely axial relative movement and are separable from each other by an actuation of the fastening devices.
According to one example of realisation, the user has to push the actuation arms of the syringe gripping levers towards the inside in order to separate the syringe from the pipette. In this, the gripping arms unlock the syringe flange and the unlocking cams of the syringe gripping levers press the actuation arms of the plunger gripping levers, so that the same unlock the syringe plunger. Preloaded helical springs of a flange abutment press towards the axial opening of the repetition pipette in order to eject the syringe. For detaching the syringe from the pipette, the two syringe gripping levers have to be actuated with two fingers at the same time.
From DE 10 2005 023 203 A1, the entire contents of which are incorporated herein by reference, respectively or US 2006 26 32 61 A1, the entire contents of which are incorporated herein by reference, respectively, respectively, a pipette is known in which the syringe can be detached from the pipette by actuating only one detachment trigger. For this purpose, the syringe gripping levers have releasing levers projecting towards the inside on the actuation arms in a pipette which is provided with fastening devices for reversibly fastening syringes according to DE 10 2005 023 203 A1 or US 2006 26 32 61 A1, respectively. Further, a transfer element, shiftably guided in the pipette housing transversely with respect to the releasing levers in at least one guiding, can be brought into abutment on the two releasing levers with an abutment surface at the front side by shifting it in the guiding. In addition, a detachment trigger displaceably arranged in the pipette housing is coupled with the transfer element, in order to shift the transfer element in the guiding when the detachment trigger is displaced. For actuating the actuation members of the plunger setting devices and the detachment trigger, the user has to change his/her grip.
From DE 199 17 907 A1, the entire contents of which are incorporated herein by reference, respectively, a pipette for a pipette system with pipette and syringe is known, which has a cylinder, a flange and a plunger with a plunger head. In a pipette housing, a plunger setting device is axially shiftable. On the pipette housing, a cylinder gripping device fro the flange of the syringe is mounted to be axially accessible. On the plunger setting device and shiftable with the same, a plunger gripping device for the plunger head is mounted to be axially accessible. Further, an actuation device for the cylinder gripping device and the plunger device is stationarily mounted on the pipette housing. The gripping devices feature radially closable cylinder gripping levers and plunger gripping levers, which are normally in the gripping position and which can be brought into a releasing position by actuating the actuation device, in which the flange and the plunger head of a syringe are released for take-out or for reception. On the pipette housing, the actuation device has a central actuation element, actuatable from the outside, whose movement when actuated is transferred to the cylinder gripping levers via a first force transmission train on the one hand, and on the other hand to the plunger gripping levers via a second force transmission train.
The cylinder gripping levers or the plunger gripping levers can be in the gripping position under spring force, and can be brought into the releasing position against the spring force. Further, two cylinder gripping levers and two plunger gripping levers standing opposite to each other can be provided, and the central actuation element can extend to both of the two pairs of gripping levers in the pipette housing. The force transmission trains can be constituted by wedge mechanisms between the actuation element and the respective gripping levers. According to a further embodiment, the second force transmission train is closed only when the plunger setting device is completely pushed up.
When liquid is delivered stepwise with a syringe, the plunger setting device is actuated from the upside by hand or through a motor. The actuation element, actuatable from the outside, of the actuation device is executed as an actuation key for instance, which is arranged below on one side of the pipette housing. Even with this pipette, the user has to change his/her grip, when he/she wants to actuate the actuation element for discarding a syringe after actuating the plunger setting device.